Biooptical and biofunctional properties, applications and methods of polylactic acid films

ABSTRACT

High surface energy materials with low refractive index and UV transparency wherein multilayers of similar or dissimilar materials are thermally fused together to form various functional optical requirements are provided. In some embodiments, a photocatalytic biopolymer structure comprising of a UV transparent biopolymer in integrating fused nanophotocatalytic minerals such as Tio2 used for various applications is provided. Many embodiments are based on the integration of nanophotocatalytic minerals fused to a biopolymer structure in which the biopolymer structure is UV transparent (UVT) and allows UV light to be transmitted through the biopolymer structure activating the nanophotocatalytic fused layer.

This application claims priority to U.S. Provisional Application No.61/364,306, filed Jul. 14, 2010, the content of which is herebyincorporated in its entirety by reference.

BACKGROUND Photocatalytic Reactions

In chemistry, photocatalysis is the acceleration of a photoreaction inthe presence of a catalyst. In catalysed photolysis, light is absorbedby an adsorbed substrate. In photogenerated catalysis, thephotocatalytic activity (PCA) depends on the ability of the catalyst tocreate electron-hole pairs, which generate free radicals (hydroxylradicals: .OH) able to undergo secondary reactions. Its comprehensionhas been made possible ever since the discovery of water electrolysis bymeans of the titanium dioxide. Commercial application of the process iscalled Advanced Oxidation Process (AOP). There are several methods ofachieving AOP's, that can but do not necessarily involve TiO2 or eventhe use of UV light. Generally the defining factor is the production anduse of the hydroxyl radical

The principle of photocatalytic reaction was to accelerate the nature'scleaning and purifying process using light as energy. Discovered in1960's, Dr. Fujishima of Japan found titanium metal, after irradiated bylight, could break water molecule into oxygen and hydrogen gas. Byrestructuring titanium dioxide particles in nano-scale, a number of newphysical and chemical properties were discovered. One of these newfoundeffects was photocatalytic oxidation which accelerated the formation ofhydroxyl radical, one of the strongest oxidizing agents created bynature. Using energy found in the UV light, photocatalyst titaniumdioxide could breakdown numerous organic substances such as oil grimeand hydrocarbons from car exhaust and industrial smog, volatile organiccompounds found in various building materials and furniture, organicgrowth such as fungus and mildew. In addition to its photocatalyticoxidation effect, titanium dioxide coating also exhibited hydrophilicproperty (or high water-affinity) which titanium dioxide coatingattracted water moist in the air to form an invisible film of water.This thin film of water allowed the substrate to be anti-static so thecoated surface could be easily cleaned by rinse of water. For years,titanium dioxide was used in many commodity products such as paint,cosmetics, sun blocks, and etc. It is a safe and stable substancecommonly found in our lives. Numerous applications have been developedfrom utilizing photocatalytic reaction.

When photocatalyst titanium dioxide (TiO2) absorbs Ultraviolet (UV)radiation from sunlight or illuminated light source (fluorescent lamps),it will produce pairs of electrons and holes. The electron of thevalence band of titanium dioxide becomes excited when illuminated bylight. The excess energy of this excited electron promoted the electronto the conduction band of titanium dioxide therefore creating thenegative-electron (e−) and positive-hole (h+) pair. This stage isreferred as the semiconductor's ‘photo-excitation’ state. The energydifference between the valence band and the conduction band is known asthe ‘Band Gap’. Wavelength of the light necessary for photo-excitationis: 1240 (Planck's constant, h)/3.2 ev (band gap energy)=388 nm

The positive-hole of titanium dioxide breaks apart the water molecule toform hydrogen gas and hydroxyl radical. The negative-electron reactswith oxygen molecule to form super oxide anion. This cycle continueswhen light is available

Photocatalytic oxidation is achieved when UV light rays are combinedwith a TiO2 coated filter. TiO2 refers to Titanium Dioxide. This processcreates hydroxyl radicals and super-oxide ions, which are highlyreactive electrons.

These highly reactive electrons aggressively combine with other elementsin the air, such as bacteria and VOCs. VOC is an acronym for VolatileOrganic Compounds which include harmful pollutants such as formaldehyde,ammonia and many other common contaminants released by buildingmaterials and household cleaners generally found in the home. Effectiveoxidation of the pollutants breaks down into harmless carbon dioxide andwater molecules, drastically improving the air quality.

Biopolymers

With growing environmental concerns over petrochemical products and itsenvironmentally harmful practices, new environmentally friendly polymersbeing developed as a replacement for petrochemical based plastics.Materials such as PLA (polylactic acid) such as product produced byNatureworks (Cargill) are derived from natural and rapidly renewableresources of corn. To date the vast majority of interest andcommercialization is the application of PLA for disposable packaging andother disposal products. Although thought of as a disposable plastic,PLA has many new abilities and functions that can further expand theusage of this environmentally friendly biobased technology.

Polylactic acid is not derived from petrochemical materials, but fromthe conversion of starch or cellulosic materials into dextrose then intoa lactic acid. The lactic acid is then polymerized into a range ofpolymer products. This conversion process has been documented and iscurrently commercialized. Being that PLA is not petrochemical based, ithas other unique functional and processing abilities outside that ofpetrochemicals that provides unique optical and functional propertiesoutside of the needs for basic disposalable packaging.

Plastics typically block UV such as acrylic, polystyrene, PE, PP andmost all petrochemical plastics. Currently fused quartz mineral is usedfor UV transparent applications, but is both difficult and expensive toshape or form into shapes. Secondly quartz mineral can not be easilysoften to fuse nanominerals onto its surface. Currently few materialsare UV transparent and most are expensive or classified as a hazardousmaterial. Traditionally material such as quartz or sapphire have beenused in some of these industries providing a high degree of UVstability. These material have limitations in cost, fabrication, andother limitations. Other engineered polymers such as fluropolymers havebeen used in UV transparent applications, but are hindered by cost andhealth considerations. Law suits have been won suing company's based onfluropolymer emissions and pollution.

PLA is a thermoplastic polyester derived from field corn of 2-hydroxylactate (lactic acid) or lactide. The formula of the subunit is:—[O—CH(CH3)-CO]— The alpha-carbon of the monomer is optically active(L-configuration). The polylactic acid-based polymer is typicallyselected from the group consisting of D-polylactic acid, L-polylacticacid, D,L-polylactic acid, meso-polylactic acid, and any combination ofD-polylactic acid, L-polylactic acid, D,L-polylactic acid and meso

polylactic acid. In one embodiment, the polylactic acid-based materialincludes predominantly PLLA (poly-L-Lactic acid). In one embodiment, thenumber average molecular weight is about 140,000, although a workablerange for the polymer is between about 15,000 and about 300,000. In oneembodiment, the PLA is L9000™ (Biomer, Germany), apolylactic acid)

Polylactic acid is a relatively high specific gravity as compared tocommon plastics with a specific gravity closer to engineered plasticssuch as Polycarbonate. Although similar in specific gravity topolycarbonate used in various functional arid optical products, PLA hasa much lower refractive index. In addition due to the unique molecularstructure and materials, PLA is virtually transparent in UV wavelengthspectrum as compared to polycarbonate and other common plastics thathave very high UV absorption rates. From this PLA does not have visibleor UV degradation or yellowing as found in common plastics. UVtransparency and a low refractive index can have a myriad ofapplications.

UV Resistance and UV Transparency

It has been discovered the PLA has very good UV resistance in regards toUV degradation. Various tests have been performed in UV weatherometersshowing that PLA does not yellow when exposed to exterior light. Inaddition, tests based on UV-visible photospectrometers show that PLA istransparent the UV A, UV B, and in most of the UV C ranges. This showsthat the material allows full transmission of UV waves.

Other materials such as polycarbonate have high degrees of clarity inthe visible light spectrum but have high degrees of UV absorption. Mostpolymers are carefully measured for their UV absorption due to the factthat the absorption of UV has a significant relationship to UVdegradation of the polymers. Polymers are vary greatly in theirresistance to weathering, such as polymethylathacrylate (PMMA) andpolytetrafluosoethylene (PTFE) are transparent to UV radiation and hencenot susceptible to photodegradation. Materials such as PTFE and PMMA areconsidered “UV Transparent” materials

According to data obtained, the following show a specific wavelengthwherein the material starts to absorb UV-visible wavelengths:

PET 420 nm Polycarbonate 330 nm PLA 240 nm

UV or ultra violet radiation is a shorter wavelength than visible lightspectra. The following represents the areas of various UV energyclassifications:

UV A Long wave (black light) 315 to 400 nm UV B UB Medium wave 280 to315 nm UV C Short wave (germicidal) 100 to 280

From the above chart reference, it can be seen that PLA startsabsorption at a much shorter UV wavelength and in addition the amount ofabsorption is lower than that of a high quality PET that significantlylower than a polycarbonate material.

PLA also is unique in the fact that it has a high surface energy. PLAhas a similar range of refractive index as Fluoropolymers, but with muchhigher surface energy.

Little work has been found in the areas of measurement of variousoptical, electrical or other functional performance of PLA and variousmethods of hybridizing PLA with the addition or various additives,chemicals or nanomaterials.

Polylactic acid has a specific gravity typically around the 1.25 rangeand can produced in a transparent form. Common plastics for optical andother functional applications such as polycarbonate have specificgravities of typically 1.2 to 1.22.

The optical nature of petrochemicals is known and used for manyapplications including eyewear lens, television display screen s,protective coatings and myriad other optical applications.

Optical properties such as refractive index, UV absorption/transmissionand UV resistance are important issues related to optical propertieswithin petrochemical polymers used in optical applications.

Refractive Index

The refractive index or index of refraction is a ratio of the speed oflight in a vacuum relative to that speed through a given medium (thisquantity does not refer to an angle of refraction, which can be derivedfrom the refractive index using Snell's Law). In other words, as lightpasses from one medium to another as from air to water, the result is abending of light rays at an angle. This physical property occurs becausethere is a change in the velocity of light going from one medium intoanother. Refractive index also describes the quantity that light is bentas it passes through a single substance. This involves calculating theangle at which light enters the medium and comparing that with the angleat which the light leaves the medium.

Another view rates each substance with its own refractive index. This isbecause the velocity of light through the substance is compared as aratio to the velocity of light in a vacuum. The velocity at which lighttravels in a vacuum is a physical constant, and the fastest speed atwhich energy or information can travel. However, light travels slowerthrough any given material, or medium, that is not a vacuum. This isactually a delay from when light enters the material to when it leaves;i.e., when some is absorbed, and another part transmitted. The followingshows various refractive indices of plastics:

Specific Gravity Refractive Index Polycarbonate 1.2-1.22 1.58 PolylacticAcid 1.24-1.25 1.46 note: Range with blending (1.4 to 1.55)

The difference of refractive index between PLA and conventionalpetrochemical polymers also provides other potential functional featuresincluding electrical dielectric strength.

The dielectric constant (which is often dependent on wavelength) issimply the square of the (complex) refractive index in a non-magneticmedium (one with a relative permeability of unity). The refractive indexis used for optics in Fresnel equations and Snell's law; while thedielectric constant is used in Maxwell's equations and electronics

Thus from this basic physics the dielectric constant of PLA would belower than conventional petrochemical plastics and have variousapplications in electrical components and systems.

Fluoropolymers have been investigated for a wide range of innovativeoptical applications not only because of their possible optical claritybut also because their refractive indices are generally much lower thancompeting materials such as PMMA and PC. The refractive index for mostfluoropolymers is in the region of 1.30 to 1.45 compared with therefractive index for more traditional transparent polymers such as PMMAand PC where it is in the region of 1.5 to 1.6 (or higher). This makesthe fluoropolymers suitable for optical technology products such aswaveguides, optical filters, fiber gratings and a wide range of opticaldevices. Specialist ultra-transparent fluoropolymers are also beingdeveloped for these applications and for use in rapidly developing CMOSlithography technologies essential for the production of semiconductordevices. The optical clarity and other performance properties offluoropolymers are opening new markets and opportunities.

The usage of dissimilar materials with various refractive indexes areused for a wide range of applications for antireflective coatings, LCDflat panel screen assemblies, general optical lensing and other similarapplications. A lower or different refractive index of PLA incombination with a convention higher refractive index can have uniqueapplications and provide a tool for design of new optical based systems.

Luminous Transmittance

Luminous transmittance for various materials is provided below.

Optical glass 99.9 PMMA 92 PC 89 SAN 88 PS 88 ABS 79 PVC 76

SUMMARY

A high surface energy material with low refractive index and UVtransparency wherein multilayers of similar or dissimilar materials arethermally fused together to form various functional optical requirementsis provided. Various compositions and systems are provided incorporatinga UV transparent biopolymer structure are provided. A photocatalyticbiopolymer structure comprising of a UV transparent biopolymer inintegrating fused nanophotocatalytic minerals such as Tio2 used forvarious applications is provided. Many embodiments are based on theintegration of nanophotocatalytic minerals fused to a biopolymerstructure in which the biopolymer structure is UV transparent (UVT) andallows UV light to be transmitted through the biopolymer structureactivating the nanophotocatalytic fused layer. A UV Transparentbiolamiante either including a photocat within the biolaminate materialor as a coating of photocats with various binders are included withinthe scope of the invention.

DETAILED DESCRIPTION

A high surface energy material with low refractive index and UVtransparency wherein multilayers of similar or dissimilar materials arethermally fused together to form various functional optical requirementsis provided. Various compositions and systems are provided incorporatinga UV transparent biopolymer structure are provided. A photocatalyticbiopolymer structure comprising of a UV transparent biopolymer inintegrating fused nanophotocatalytic minerals such as Tio2 used forvarious applications is provided. Many embodiments are based on theintegration of nanophotocatalytic minerals fused to a biopolymerstructure in which the biopolymer structure is UV transparent (UVT) andallows UV light to be transmitted through the biopolymer structureactivating the nanophotocatalytic fused layer. A UV Transparentbiolamiante either including a photocat within the biolaminate materialor as a coating of photocats with various binders are included withinthe scope of the invention.

The invention thus provides structures that can be integrated intovarious products that are 100% “natural” comprising of rapidly renewablebiopolymers and natural nanominerals in addition provide an “activedevice” for the reduction or elimination of bacteria, viruses, VOC's andodor for a wide range of markets.

In some embodiments, a UV transparent biopolymer in the form of a fusedparticle sheet, extruded sheet, or molded structure wherein thebiopolymer structure has fused nanophotocatalytic minerals fused to onesurface is provided. The other side of the structure can contain a UVlight source such as a fluorescent tube, compact fluorescent light or UVLED in which the UV light is transmitted through the biopolymerstructure and activate the nanophotocatalytic fused layer.

In some embodiments, a UV transparent stabilized biopolymer composition,having a high level of UV transmission and UV transmission retention, isprovided. The composition is very effective in retaining its UVtransmission under various environmental conditions. By UV radiation, asused herein is meant radiation defined in UV-A, UV-B and UV-C spectratypically having a wavelength of 400 nm or shorter, or a light sourcethat contains a certain portion of UV radiation that has a wavelengthshorter than 380 nm.

In other embodiments, various forms of UV transparent biopolymerstructures including independent fused particle sheets, extruded sheetand molded shapes are provided.

In yet other embodiments, the invention also integrates UV sources fromfluorescent lighting tubes, compact fluorescent lighting and UV LEDsources. The invention further comprises structures such as fluorescentlighting diffusers and covers.

In still further embodiments, the invention further comprises thecombination of a nanophotocatalytic layer in combination with a UVtransparent device, structure, lighting covers and diffusers, panel,sheet or film.

The invention further comprises integration of these structures intovarious devices, products, and applications for reduction of VOC's, airexchanging, bacteria reduction, water purification and otherapplications. The invention can be used for a wide range ofapplications, products and devices for the reduction/elimination ofbacteria, viruses, VOC's and odor in various markets.

The teachings herein may be widely applied to a variety of fields. Theteachings may be used to form films for UV sources, such reflectivefilms including multilayer antireflective films for televisions or otherscreens and continuous/disperse phase reflective polarizers for screens.Embodiments disclosed herein, including the usage of PLA films ofvarious thicknesses, have use in water treatment films, pipe, conduitand apparatus (UV), germicidal film, solar cell films, medical testcontainers, and UV photolithography.

Biopolymers

Biopolymer based biolaminates are environmentally friendly andpetrochemical free, and also have unique functional features includingUV transparency and high degree of resistance to UV degradation.Biopolymer biolaminates are highly polar nature also provide a highdegree of ability to load various levels of fillers or functionalmaterials such as photocatalytic particles or nanoparticle or blendsthereof. The UV transparency and resistance of UV degradation providesunique properties for photocatalytic materials such as nano Tio2 andother similar forms of nanophotocatalytic materials.

PLA has a higher specific gravity but a lower refractive index comparedto polycarbonates.

Specific Gravity Refractive Index Polycarbonate 1.2-1.22 1.58 PolylacticAcid 1.24-1.25 1.46 note: Range with blending (1.4 to 1.55)

Polylactic acid can be modified with various biobased additives andvarious petrochemical additives to “adjust” various functional andoptical properties. Examples include, but are not limited to: acrylics,polycarbonates, silicon, fluorine based chemistry, standardpetrochemical plastics, UV functional additives, nanomaterials and othersuch modifiers. Although these embodiments are based on the usage ofPLA, the addition of small portions of these other additives ormodifiers can be used to make adjustments in these various optical,electrical or functional properties.

Because of its UV Transparency, PLA does not substantially degrade basedon exposure to UV light or exterior sunlight containing UV spectra.Photo-degradation in plastics is caused by the UV component of solarradiation, that is radiation of wavelength from 0.295 to 0.400 nm. Thisis absorbed by some plastics and causes the breakage of bonds in thepolymers leading to photo-oxidation. Being PLA is transparent at abroader range of UV wavelengths, PLA is not susceptable to this form ofmolecular bond breakages leading to yellowing or photodegradation.

PLA is unique to have a lower refractive index, with a high specificgravity, UV transparency and low UV degradation. In addition the abilityto modify PLA by means of processing or by compounding of additives willshow that these forms of functional PLA can have broad rangingapplication for optical, electrical and functional applications.

Various waxes such as Camuba wax are compatitible with PLA and matchrefractive index. Camuba wax has a refractive index of 1.45. Othermaterial or waxes such as a soybean oil wax or “hydrogenated oil” basedwax also provides a lower or matching refractive index.

PLA has a similar range of refractive index as Fluoropolymers and isequal or better in UV transmission based on the PLA formulation or PLAcomposite makeup. Polylactic acid as a specific gravity typically aroundthe 1.25 range and can produced in a transparent form. Common plasticsfor optical and other functional applications such as Polycarbonate havespecific gravities of typically 1.2 to 1.22 but are UV opaque.

PLA's current refractive index of 1.4 is within the upper range of thefluoropolymers. With “biomodification” and additives, PLA's refractiveindex may be manipulated within a similar range.

Biopolymers have a unique ability to be “UV Transparent” at UVwavelengths primarily in the UV spectra and at the 388 nm at the primarywavelength of the TiO2 photocatyst optimal performance range. Secondly,the polar nature of the biolaminate primary biopolymer also can includeother functional minerals such as natural quartz or other minerals thatare also UV transparent.

The biopolymer structure can include filers or additives that are alsoUV transparent as not to decrease the efficiency of UV transmission thatdrives the photocatatlyic reaction. Fillers such as nanoquartz, fusedsilica, fluropolymers, or particles of fluropolymers and specializedacrylics can be blended with the biopolymer as long as they also havesimilar UV transparency characteristics as the UV transparentbiopolymer.

While polylactic acid (PLA) is specifically discussed herein, otherbiopolymers having similar UV transparency, for example celluloseacetate, may alternatively be used.

Materials of low refractive index or UV transparent are typicallyexpensive and difficult polymeric films. In many cases such as influorinated polymer used for AR, these polymers and the common additionof silicon reduces the surface energy of the film where adhesion todissimilar material is difficult.

The unique refractive index of PLA is closely matched to that of theabove art. The above art has limitation in regards to adhesion. PLA alsohas a unique surface energy averaging about 40 DYNE and can be easilymodified. This surface energy level is optimal for printing and adhesionwhile still providing a low refractive index and UV transparency.

PLA Summary

Polylactic acid is a relatively high specific gravity as compared tocommon plastics with a specific gravity closer to engineered plasticssuch as Polycarbonate. Although similar in specific gravity topolycarbonate used in various functional and optical products, PLA has amuch lower refractive index. In addition due to the unique molecularstructure and materials, PLA is virtually transparent in UV wavelengthspectrum as compared to polycarbonate and other common plastics thathave very high UV absorption rates. From this PLA does not have visibleor UV degradation or yellowing as founding common plastics.

PLA also is unique in the fact that it has a high surface energy thatpromotes the ability to coat the material with various optical coatingssuch as antireflective, photochromic, and other coating methods foroptical materials and products. PLA surface energy is typically 40 Dyneand can be further modified by corona treatments and other means tochange surface energy.

Spectraphotometry tests show that polylactic acid is UV transparent andprovides additional optical properties in the visible and UV spectra.The ability to integrate UV transparent mineral, nanominerals and otherUV transparent polymers provides the ability to create new materials,devices, and products that meet the need for UV transparency and providean environmentally friendly solution. This invention of UV transparentbiopolymers or biocomposites also can be molded, postformed, or shapedinto complex shapes that are difficult to produce using quartz.

In some embodiments, modifications to the refractive index of PLA areprovided. Such modifications may be done using a wax, wherein the waxhas a refractive index at or below 1.45. Alternatively, suchmodifications may be done using acrylates wherein the polymer blend canhave a modified UV transparency and refractive index. To better matchthe refractive index of PLA, low Tg acrylics such as ethyl acrylate orbutyl acrylate may be used.

Titanium Dioxide

TiO2, titanium dioxide, or titania is the naturally occurring oxide oftitanium and is known for the stability of its chemical structure, itsbiocompatibility and physical, optical and electrical properties.Titanium dioxide occurs in nature as the well-known naturally occurringminerals rutile, anatase and brookite. Zinc oxide and Titanium dioxide,particularly in the anatase form, are photocatalysts under ultravioletlight This has been discussed for example in the report from Maness etal (Maness et al, Applied and Environmental Microbiology, 65, (1999)4094-8). Recently, it has been found that titanium dioxide, when spikedwith nitrogen ions, is also a photocatalyst under visible light Titaniumdioxide is a photocatalyst when irradiated with light The light isabsorbed by the oxide material triggering a chemical reaction that, inthe presence of water, ends with the oxidation of water to createhydroxyl radicals. The reaction can also produce oxygen radicals or evenoxidize organic materials directly Moreover, free radicals activelymodulate immune responses, activate macrophages and stimulate thehealing process

TiO2 is a potent photocatalyst that can break down almost any organiccompound when exposed to sunlight and be used for water and airtreatment as well as for catalytic production of gases. The generalscheme for the photocatalytic destruction of organics begins with itsexcitation by suprabandgap photons, and continues through redoxreactions where OH radicals, formed on the photocatalyst surface, play amajor role.

Photocatalysts

Photocatalysts, upon activation or exposure to sunlight, establish bothoxidation and reduction sites. These sites are capable of preventing orinhibiting the growth of algae on the substrate or generating reactivespecies that inhibit the growth of algae on the substrate. In otherembodiments, the sites generate reactive species that inhibit the growthof biota on the substrate. The sites themselves, or the reactive speciesgenerated by the sites, may also photooxidize other surface contaminantssuch as dirt or soot or pollen. Photocatalytic elements are also capableof generating reactive species which react with organic contaminantsconverting them to materials which volatilize or rinse away readily.Photocatalytic particles conventionally recognized by those skilled inthe art are suitable for use with the present invention. Suitablephotocatalysts include, but are not limited to, TiO2, ZnO, WO3, SnO2,CaTiO3, Fe2O3, MoO3, Nb2O5, TixZr (1−x)O2, SiC, SrTiO3, CdS, GaP, InP,GaAs, BaTiO3, KNbO3, Ta2O5, Bi2O3, NiO, Cu2O, SiO2, MoS2, InPb, RuO2,CeO2, Ti(OH) 4, combinations thereof, or inactive particles coated witha photocatalytic coating. In other embodiments, the photocatalyticparticles are doped with, for example, carbon, nitrogen, sulfur,fluorine, and the like. In other embodiments, the dopant may be ametallic element such as Pt, Ag, or Cu. In some embodiments, the dopingmaterial modified the bandgap of the photocatalytic particle. In someembodiments, the transition metal oxide photocatalyst is nanocrystallineanatase TiO2

Nanometer photocatalyst may be made from TiO2 grains, the sizes of whichare under 20 nm. After they absorb UV in sunshine and illuminatelamp-house, the electrons on them are activated by UV and flies off,then produce electron holes, which have strong oxidation ability (theholes are produced, when the electrons are flying off). The electron hasstrong deoxidization ability, will produce oxidation anion free radicalsand oxyhydrogen free radicals after reacting with H20 and O2 in air.They have strong oxidation ability, and can decompose the organic,contaminants, fume, and bacteria into hurtles CO2 and H2O. At the sametime, the electrons make deoxidization reaction to deoxidize the oxygenin air

Photocatalysts have strong efficacy in preventing mildew. The clothpackaged food utilizing photocatalyst can obviously suppress goingmould. It can keep fresh in 10 days. According to the experiments, theefficacy spraying over 1000 square meters is equivalent to the airpurifying ability of 70 silver birch.

Photocatalyst Nano-TiO2 super disinfections power has been verified tokill bacteria, virus and fungi, as well as to eliminate foul smell. Ithas been tested with a series of experiences by different authoritiesand academic bodies, Food Research Center, Universities, etc, and havingvery good performance. Photocatalyst. Nano-TiO2 can kill Pseudomonasaeruginosa, Influenza virus, MRSA, Tubercle Bacillus, etc. PhotocatalystNano-TiO2 also has been tested and can eliminate the toxic andcarcinogen gases, such VOC and formaldehyde, etc.

The threshold wavelength for titanium dioxide photocatalyst is 388 nm.At wavelengths below that the outer valence electron in the TiO2molecule simply needs to absorb enough photons to have the energy toescape.

The invention also includes various photocatalytic minerals that aredoped. This may further increase the efficiencies of the devices andsystems within this invention by increasing the light wavelength rangefrom UV as to also include lower ends of the visible light spectra.Although covered within this invention, the preferred means isphotocatalytic minerals that operate in the UV spectra.

UV Transparent Composites

UV Transparent (UVT) biopolymer composites are provided herein. The UVTbiopolymer material within this invention may be blended with variousfillers, fibers, minerals, additives, and polymer blends as long as theydo not significantly limit the UV transparent function of the UVTbiopolymer. These materials can modify the mechanical or physicalperformance of the final product or device for specific applicationsrequirements.

Fillers such as quartz, ATH and other UVT minerals can be compoundedwith the UVT Biopolymer to increase its stiffness and improve heatresistance while having minimal effect on the UVT properties.

Fiber reinforcement can also be integrated into the material includingglass fibers, mineral fibers, certain natural fibers and other commonforms of fiber reinforcement to improve the mechanical properties of thefinal shape, sheet or panel.

Other petrochemical polymer additives can also be added such asfluropolymers, and special acrylics that also have similar UVTproperties.

Applications

A PLA film may be used as an anti-reflective film for screens, such astelevision screens, and provides an interface between currentpetrochemical screen films and air. In one embodiment, an assembly isprovided wherein a low refractive index PLA is extruded into a film andused within a multilayer assembly for television screens. Oneapplication is related to that of continuous/disperse phase reflectivepolarizers used in LCD televisions that rely on the difference inrefractive index between at least two materials, usually polymericmaterials, to selectively reflect light of one polarization state whiletransmitting light in an orthogonal polarization state. In oneembodiment, an assembly of a thin PLA film in combination with a opticalgrade plastic or glass wherein the refractive index of the PLA is lowerand provides a AR coating is provided.

With the design considerations described in U.S. Pat. No. 5,882,774, oneof ordinary skill will readily appreciate that a wide variety ofmaterials can be used to form multilayer polymeric reflective mirrorfilms when processed under conditions selected to yield the desiredrefractive index relationships. The desired refractive indexrelationships can be achieved in a variety of ways, including stretchingduring or after film formation (e.g., in the case of organic polymers),extruding (e.g., in the case of liquid crystalline materials), orcoating. In addition, it is preferred that the two materials havesimilar rheological properties (e.g., melt viscosities) such that theycan be co-extruded.

Antireflective Coatings

An antireflective or anti-reflection (AR) coating is a type of opticalcoating applied to the surface of lenses and other optical devices toreduce reflection. This improves the efficiency of the system since lesslight is lost. In complex systems such as a telescope, the reduction inreflections also improves the contrast of the image by elimination ofstray light. This is especially important in planetary astronomy. Inother applications, the primary benefit is the elimination of thereflection itself, such as a coating on eyeglass lenses that makes theeyes of the wearer more visible to others, or a coating to reduce theglint from a covert viewer's binoculars or telescopic sight.

Many coatings consist of transparent thin film structures withalternating layers of contrasting refractive index. Layer thicknessesare chosen to produce destructive interference in the beams reflectedfrom the interfaces, and constructive interference in the correspondingtransmitted beams. This makes the structure's performance change withwavelength and incident angle, so that color effects often appear atoblique angles. A wavelength range must be specified when designing orordering such coatings, but good performance can often be achieved for arelatively wide range of frequencies: usually a choice of IR, visible,or UV is offered

The simplest interference AR coating consists of a single quarter-wavelayer of transparent material whose refractive index is the square rootof the substrate's refractive index; this, theoretically, gives zeroreflectance at the center wavelength and decreased reflectance forwavelengths in a broad band around the center.

The most common type of optical glass is crown glass, which has an indexof refraction of about 1.52. An optimum single layer coating would, haveto be made of a material with an index equal to about 1.23.Unfortunately, there is no material with such an index that has goodphysical properties for an optical coating. The closest ‘good’ materialsavailable are magnesium fluoride, MgF2 (with an index of 1.38), andfluoropolymers (which can have indices as low as 1.30, but are moredifficult to apply). MgF2, on a crown glass surface, and bare glass givereflectances of about 1% and 4%, respectively. MgF2 coatings performmuch better on higher-index glasses, especially those with index ofrefraction close to 1.9. MgF2 coatings are commonly used because theyare cheap, and when they are designed for a wavelength in the middle ofthe visible band they give reasonably good anti-reflection over theentire band

Antireflective polymer films (“AR films”), or AR coatings, are becomingincreasingly important in the display industry. New applications arebeing developed for low reflective films and other AR coatings appliedto articles used in the computer, television, appliance, mobile phone,aerospace and automotive industries.

AR films are typically constructed by alternating high and lowrefractive index polymer layers in order to minimize the amount of lightthat is reflected. Desirable features in AR films for use on thesubstrate of the articles are the combination of a low percentage ofreflected light (e.g. 1.5% or lower) and durability to scratches andabrasions. These features are obtained in AR constructions by maximizingthe delta RI between the polymer layers while maintaining strongadhesion between the polymer layers.

The low refractive index polymer layers used in AR films are usuallyderived from fluorine containing polymers (“fluoropolymers” or“fluorinated polymers”), which have refractive indices that range fromabout 1.3 to 1.4. Fluoropolymers provide unique advantages overconventional hydrocarbon based materials in terms of high chemicalinertness (in terms of acid and base resistance), dirt and stainresistance (due to low surface energy), low moisture absorption, andresistance to weather and solar conditions.

The refractive index of fluorinated polymer coating layers is dependentupon the volume percentage of fluorine contained within the layers.Increased fluorine content decreases the refractive index of the coatinglayers.

However, increasing the fluorine content also decreases the surfaceenergy of the coating layers, which in turn reduces the interfacialadhesion of the fluoropolymer layer to the other polymer or substratelayers to which the layer is coupled.

Other materials investigated for use in low refractive index layers aresilicone-containing polymeric materials. Silicone-containing polymericmaterials have generally low refractive indices. Further,silicone-containing polymeric coating layers generally have highersurface energies than fluoropolymer-base layers, thus allowing thesilicone-containing polymeric layer to more easily adhere to otherlayers, such as high refractive index layers, or substrates. This addedadhesion improves scratch resistance in multilayer antireflectioncoatings. However, silicone-containing polymeric materials have a higherrefractive index as compared with fluorine containing materials.Further, silicone-containing polymeric materials have a lower viscositythat leads to defects in ultra-thin coatings (less than about 100nanometers).

Thus, it is highly desirable to form a low refractive index layer for anantireflection film having increased fluorine content, and hence lowerrefractive index, while improving interfacial adhesion to accompanyinglayers or substrates.

Accordingly, an antireflective coating using PLA as described herein maybe used.

Optical Mirror Films

Multilayer optical mirror films as used in conjunction with the presentinvention exhibit relatively low absorption of incident light, as wellas high reflectivity for off-axis as well as normal light rays. Theunique properties and advantages of the multi-layer optical filmprovides an opportunity to design highly efficient backlight systemswhich exhibit low absorption losses when compared to known backlightsystems. Exemplary multilayer optical mirror film of the presentinvention is described in U.S. Pat. No. 6,924,014, which is incorporatedherein by reference (see Example 1 and Example 2). Exemplary multilayeroptical mirror film includes a multilayer stack having alternatinglayers of at least two materials. At least one of the materials has theproperty of stress induced birefringence, such that the index ofrefraction (n) of the material is affected by the stretching process.The difference in refractive index at each boundary between layers willcause part of ray to be reflected. By stretching the multilayer stackover a range of uniaxial to biaxial orientation, a film is created witha range of reflectivities for differently oriented plane-polarizedincident light. The multilayer stack can thus be made useful as amirror. Multilayer optical films constructed accordingly exhibit aBrewster angle (the angle at which reflectance goes to zero for lightincident at any of the layer interfaces) which is very large or isnonexistent. As a result, these polymeric multilayer stacks having highreflectivity for both s and p polarized light over a wide bandwidth, andover a wide range of angles, reflection can be achieved.

UVT PCO Coated Panel or Film

A UVT biopolymer can be extruded into the form of a sheet or film whichthen can be coated using various optical coating methods such asantireflective, photochomic, refective and other coatings commonly usedin optical coatings. The photocatalytic materials can be eitherintegrated into these coating layers or applied separately over thesurface of the optical coatings. In one embodiment, an assembly whereina UV Transparent PLA film is extruded into a film or tube used forgermicidal UV apparatus is provided.

Lighting Diffuser

Commercial ceiling fluorescent lighting fixtures currently use plasticacrylic or polystyrene covers or diffuser panels to protect the bulb ifbroken and to disperse the light more uniformly within a room. Bothacrylic and polystyrene are opaque or block UV spectra. The inventionintegrates a sheet or UVT embossed structure as a direct replacement forthe diffuser. A nanophotocatalytic coating or fused layer ofnanominerals are fused to one side of the structure. The UV source inthe form of a fixed fluorescent, UV led or other UV lighting sources areon the alternate side allowing the UV spectra to be efficientlytransmitted thorugh the UVT structure activating the nanophotocatalyticlayer. The resulting light panel can be installed in standard commercialceiling fixtures for new or remodel construction and provide bacteria,virus, VOC and odor reduction for facilities.

A UVT PCO lighting diffuser comprises of a panel either extruded, moldedor of fused particles into standard dropped ceiling lighting coverssizes. The panel is coated with a PCO layer and the panel can bereheated to fuse the nanoparticles onto the surface. The UVT panel canalso include transparent colored particles for aesthetic and brandingrecognition. The panel can also include decorative inclusion includingrecycled glass, fibers and minerals as long as they do not significantlyreduce the UV Transparent function of the panel. The UVT PCO lightingdiffuser has various embossed or molded textures as to better improvethe light diffusion.

VOC Exchanger Devices

The UVT panels coated with a nanophotocatalytic layer in which a UVlight source passes through the UVT panel to activate thenanophotocatalytic layer can be designed in various air exchangerdevices. Flat or molded UVT biopolymer panels are extruded, molded orpostformed into panels that are placed inside of an air enclosure. Airis blown or pulled through the enclosure by means of a fan. A UV sourceis placed on the side or outside of the enclosures wherein UV light canpenetrate into the enclosure. Multiple panels of the UVT biopolymernanocoated panels line up as to allow linear laminar flow through theenclosure without restriction. The UV light from the side or outside ofthe enclosure penetrates to the first UVT PCO panel and UV light willcontinue to pass through reaching the next panel. This allow for amultiple panels to be stacked to increase surface area and efficencieswithin the enclosure for the reduction of VOCs, bacteria and odor. Thedevice can also include a filter mechanism.

This mechanism or device can be built as a stand alone VOC exchangerwherein it recycles the air within a room. This also can be designed tofit within exhaust pipes to remove VOC's prior to being emitted to theoutside environment.

UVT PCO Window Film.

A thin film of a UVT biopolymer is extruded using standard filmextrusion methods. Other UVT materials, fillers, additives, tints,colorants, plasticizers and processing aides can be added as long asthey do not significantly reduce the UV transparent function of thefilm. After extrusion the film is coated with a PCO material layer andoptionally reheated to fuse the nanoparticles of the PCO onto the UVTbiopolymeric film. The film can also be secondary coated with variousantireflective or optical coatings. The film also can comprise of anwindow adhesive layer for window film applications again as long as theadhesive has minimal effect on the UV transparency of the UVT biopolymerfilm.

UVT PCO Water Purification Device and Hydrogen Generation.

A UVT biopolymer tube shape structure can be made from extrusion orpostforming. A PCO coating is fused to the inside of the tube and a UVsource mounted on the outside of the tube. Water flowing through thetube is processed by means of the nanophotocatalytic and residual UVlight spectra that also can act as a germicide. Modifications to thisstructure may also have applications for the generation of Hydrogen as arenewable fuel. The device would utilize both direct sunlight and aseparate UV light source underneath the UVT/PCO biopolymer layer inwhich water can be stored and converted into hydrogen.

UVT PCO Molded Device

A UVT PCO molded device comprises of a injection molded UVT biopolymerwherein a UV or full spectra including UV source can be inserted intothe middle or center of the molded device. A nanophotocatalytic layer isapplied and fused to the outside surface of the molded device. Thedevice can be used in various applications for clothing, shoes,textiles, water purification, and medical devices for the reduction ofVOC, odor, bacteria and viruses.

UV Crosslinking Applications

The potential of “UV TRANSPARENT” has other potential applications incoatings wherein UV curing technology may have applications. One examplewould be wherein a molten PLA blended with a photoinitiator would beextruded and subjected to UV curing to obtain crosslinking.

Fluorescent Lighting

Fluorescent bulbs commonly used in drop ceiling lighting fixturesresidual UV spectra provides sufficient UV source to activate thephotocatylitic surface through the UV transparent structure or device. Afluorescent lamp or fluorescent tube is a gas-discharge lamp that useselectricity to excite mercury vapor. The excited mercury atoms produceshort-wave ultraviolet light that then causes a phosphor to fluoresce,producing visible light. A fluorescent lamp converts electrical powerinto useful light more efficiently than an incandescent lamp. Whilelarger fluorescent lamps have been mostly used in commercial orinstitutional buildings, the compact fluorescent lamp is now availablein the same popular sizes as incandescents and is used as anenergy-saving alternative in homes. The phosphor fluoresce process isnot 100% efficient and thus a percentage of UV light is emitted fromcommon fluorescent tubes.

Fluorescent lighting typically coming in long tubes for ceilingcommercial fixtures and in the form of compact fluorescent lighting as adirect replacement for incandescent bulbs. Depending on the varioustype, brand and phosphorous, the amount of residual UV emissions maychange.

UV and LED Sources

Other forms of UV sourcing can be used within this invention includingUV LED. UV LED or Ultra violet light emitting diodes, are currently usedin the printing industry, air filtration and other industrial areas.They provide a good UV source with minimal power input requirements.Applications within this invention may not require full spectrumlighting or visible light, thus UVLED generating a narrow UV light bandspectra at or around the 388 nm wavelength would provide sufficient UVto activate the photocatalytic function of the fused nano materiallayer.

LED Drivers can be in the form of individual light components, sheet, orarrayed lenses. LEDS can be standard commercial LED, OLED, UV LED andblends thereof.

Other forms of integrated sources can include Plasma induction, quantumdots, and other lighting source technology that provide the potentialfor a full spectrum of light.

Fixtures

In commercial lighting, fluorescent bulbs are required to be covered dueto potential breakage of the bulbs. In addition these covers provide alight “diffusing” function to distribute the light more evenlythroughout a room.

Currently plastic diffusers are used to disperse the light from tubes.Typically these plastics are made from acrylic or polystyrene. Thesetypes of petrochemical plastics block most all of the UV spectra.Biopolymers such as polylactic acid are not petrochemically derived andhave a unique molecular structure that allows for the transmission of UVfrequencies through the material.

In optics, a diffuser is any device that diffuses or spreads out orscatters light in some manner, to give soft light. Diffuse light can beeasily obtained by making light to reflect diffusely from a whitesurface, while more compact optical diffusers may use translucentobjects. Commercial lighting is commonly done in healthcare,institutional, and many commercial buildings through dropped ceilinglighting. Drop ceiling lighting comprises of a metal enclosure, ballastand fluorescent tube lighting. The lighting is covered with apetrochemical plastic diffuser.

UVT Biopolymer Structures

Extruded film or sheet structures—UVT (UV transparent) biopolymerstructures can be extruded into sheet or film materials that can beembossed within the extrusion process. The UVT biopolymer is meltextruded by using a sheet die at various desired thicknesses typicallyranging from 0.002″ to 0.5″ and more commonly from 0.010″ to 0.125″. Theextruded sheets can also comprise of various UVT fillers, fibers, andadditives that are also UV transparent, but provide additionalmechanical or physical properties enhancements or provide additionalprocessing aid. Sheet are then coated

Particle Fusion—UVT Particle Fusion structure are comprised of neatpolylactic acid or other UV transparent biopolymer pellets wherein thepellets are formed into a layer in a mold and heated to a temperaturebetween its melting point and its glass transition temperature. Thisallows the pellets to form into individual spheres, fuse together, butstill maintain distinct boundary conditions. This allows the ability forunique light diffusion. The individual particles can also be coated witha transparent paint, dye of colorant and blended with various colors orclear particles as to provide a unique aesthetic design for particlefused UVT structures.

Injection or continuous shapes—Polylactic acid or other UVT biopolymerscan typically be injection molded into complex 3D shapes using standardinjection molding processes. UVT biopolymer molded structures can bedesigned into various products wherein a UV source is inside of thestructure and the nanophotocatalytic layer is outside of the structureallowing UV transmission as to activate the photocatalytic function ofthe device.

Rotational Molded—Polylactic acid or other UVT biopolymers can beprocessed into a powder or fine grind and molded into a hollow shape bymeans of standard rotational molding. An metal mold is rotated undersufficient heat conditions as to melt the powder and coat the moldwalls. Once cooled the hollow structure can be coated with thenanophotocataltic material.

These UVT biopolymer structures are all UV transparent and can alsocomprise of other UVT materials, fillers, polymers, and fibers as toprovide a core structure for nanophotocatalytic mineral fusion on theirsurfaces and allowing UV transmission through the structure from a fixedand/or constant UV source.

Methods of Making PLA Processing

Blend of fluoropolymer powders with a PLA film—The blending of fineparticles of fluoropolymers can act as a suspension filler with PLAextrusion in combination with the viscoelastic extrusion process forfilms. Generally, processing may be at temperatures sufficient to flowthe PLA, but not the fluoropolymer. The film can be post treated toincrease the amorphous level and clarity of the final film product. Theresulting film “may” have a lower refractive index based on the blendlevels of the materials. Other “high melting point” polymers can beprocessed into fine or nano particles that also can be processed in thesame manner.

In some embodiments, various natural waxes or oils may be compounded tomodify refractive index and UV filtering or transparency function.

Nano Grinding and Spraying

Tio2 is ground into a nanosized particles and suspended in a wateremulsion which can be sprayed into the surface of the UVT structures.

Fusion of Nanominerals to UVT Biopolymer Structure

The UVT Structure in the form of an extruded sheet, fused particlesheet, or molded form is preheated to a specific temperature below themelting point of the UVT biopolymer, but above the glass transition ofthe biopolymer. The nanomineral water emulsion is sprayed onto thesurface and can be reheated to drive off residual moisture. The highlypolar surface of the UVT biopolymer structure in combination with theheating provides for a firm fusion of the nanoparticles onto the activesurface. The final nanocoated is heated below the melting point of theUVT biopolymer structure to assist fusing the nanoparticles onto thesurface.

A lighting diffuser can be produced by extrusion method or embossing aprismatic pattern into the extruded biopolymer sheet. An alternativemethod is wherein pellets of UV transparent biopolymer are placed into asheet mold or on a continuous belt and placed in an oven. The pelletsare heated to a point below the melting point, but above its Tg pointwherein the pellets soften and form into spherical shapes. The shapesfuse together into a sold material, but maintain independent boundariesfor each spherical pellet. While still at a relatively hot condition,nanomimerals can be sprayed or coated onto the surface of the UVtransparent fused panel.

A second method of applying the PCO coating to the UVT Biopolymer iswherein a UV transparent carrier liquid is added to the nanominerals anddirectly applied to the UVT structure. In this form of coating a alkalimetal silicate can be used. The coating composition of the presentinvention generally includes a dispersion of photocatalysts having amean cluster size of less than about 300 nm and an alkali metal silicatebinder. The dispersion can be made by mixing the photocatalysts, adispersant and a solvent. Preferably, the photocatalysts are transitionmetal oxides. Particularly preferred photocatalysts include crystallineanatase TiO2, crystalline rutile TiO2, crystalline ZnO and combinationsthereof. The coating composition has a solid weight percentage ofphotocatalysts in the range of about 0.1% to about 90%. Preferred weightpercentage is in the range of about 30% to about 80%. Examples ofsuitable dispersants include inorganic acids, inorganic bases, organicacids, organic bases, anhydrous or hydrated organic acid salts andcombinations thereof. Suitable solvents can be any solvents thatdissolve the dispersant used. Examples of suitable alkali metal silicatebinders include lithium silicate, sodium silicate, potassium silicate,and combinations thereof. Applying the coating composition onto a basearticle, followed by heating to elevated temperatures in a oven or othersuitable apparatus, produces a photocatalytic coating with improvedtransparency that exhibits desirable photoactivity.

EXPERIMENTS Experiment 1 Green Filtering

A modified PLA film processed using viscoelastic processing with asoybean hydrogenated wax were extruded into a 0.005″ thick film. Thefilm was then reverse printed using a solvent based inkjet printingsystem. A substrate of a smooth MDF and a substrates of a highlytextured mineral wood composite were prepared and sprayed with a waterbased heat activated urethane adhesive. The thin film was lowtemperature formed using a vacuum forming system and fused of thesurface of the composite substrate.

A second matching group of substrates were prepared and a standard PETand PVC film were applied.

The modified PLA samples fused to the substrates were evaluated by colorusing indoor light. The samples were taken outside into direct sunlightand a significant color shift was see wherein any printed image shiftedto a very strong light green color. We believe this shows some opticalor UV filter effect. We are also assuming at this time that this effectis caused due to the unique interface or chemical state at the interfaceof the ink and the PLA films. The PET samples were also submitted tooutside light and shown no change in color.

Experiment 2 UV Resistance and UV Spectrophotometry

PLA has been tested for UV resistance by The Design Shop and by theprimary manufacture of PLA (Cargill). Surprisingly, the UV resistance ofPLA is better than the best petrochemical polymers includingpolycarbonate. In addition we obtained spectrophotometer work comparinga PET to a PLA showing very low to no absorbance in the UV spectra inboth the UV A & B ranges as compared to high absorption with the PET inthese ranges.

Experiment 3 Change in Crystalline and Amorphous States

Although not Limited to viscoelastic processing of PLA for surfacing,viscoelastic processing maintains a high degree of crystallinity withinthe PLA films. Viscoelastic processing integrates lower temperatureprocessing or modified temperature profiles in combination with variousadditives including hydrogenated soybean wax that maybe acting as anucleating agent. The resulting film is semitransparent, but also has aunique optical effect that highlights the decorative printing patternsof our material. In further, post processing such as thermofoiling, wesee a definite change in clarity at 140 F to 180 F wherein, theBiolaminate film increases its clarity significantly. This can beadjusted by adjusting the range and processing parameters ofthermofoiling.

Experiment 4

Polylactic acid pellets from Natureworks were placed into a mold andheated to its melting temperature under pressure creating a thin sheet.A second sheet was produced by means of standard extrusion processing.The material samples were subjected to photospectrometer tests. Theresults showed that the material transmitted UV frequencies into the UVA and UV B frequencies at high levels of UV transmission (over 90%) atthe targeted 388 nano meter range.

Experiment 5

Polylactic acid pellets were layered into a sheet mold two pellets indepth. The mold was placed in an oven at 340 F for 8 minutes. Thepellets first became “spherical” as they reach their softening point,but below their melt point. The pellets fused together and once cooledbecame a solid sheet of high integrity. The individual pellets were allin a spherical shape. The panel was then placed in a light fixture andcompared to a standard acrylic light diffuser (crystal pattern). Thelight from the PLA sphere panels was highly dispersed at all angleswhereas the standard acrylic panel shown a strong focus in the middleand quickly lowered in light intensity as the angle of your eyedecreased.

Experiment 6

Cellulose acetate and polylactic acid were individually extruded into asheet and measured for its UV transmission at 388 nm in comparison toacrylic. The acrylic was less than 10% transmission at this UV spectrawhereas the PLA and cellulose acetate shown a very high degree oftransmission greater than 90%.

Experiment 7

Nanoquartz was blended with PLA at a level of 10% by weight and extrudedinto a sheet sample. The sample was submitted to photospectroscopy. Thematerial shown the same UV transparency as the neat PLA comparisonsample with minimal loss in the UV A spectra.

Experiment 8

Nanoquartz mineral was coated over the surface of a polylactic acidsheet. The material was heated to a temperature above its Tg and belowit melting point. The part was cooled. In using a brush on the surfaceto attempt to remove the quartz. Little to no quartz was removed fromthe surface.

Experiment 9

nanoTio2 photocatalytic mineral was coated on the top surface of anextruded PLA sheet. A UV light source was placed on the oppositebackside of the PLA sheet. Smoke was blown into a container and placedon top of the PLA sheet. The photocatalytic reaction with UV lighttransferring through the UV transparent PLA reduced and eliminated thesmoke in a matter of minutes.

What is claimed is:
 1. An ultraviolet transparent (UVT) biopolymerphotocatalytic structure comprising: a UVT biopolymer layer; ananophotocatalytic layer in contact with the UVT biopolymer layer; and afixed UV source positioned such that light in a uv spectra from the UVsource reaches the UV transparent biopolymer layer; wherein the UVspectra can be transmitted though the UVT biopolymer structure toactivate the nanophotocatatlytic layer.
 2. The UVT biopolymerphotocatalytic structure of claim 1, wherein the UV source is afluorescent bulb.
 3. The UVT biopolymer photocatalytic structure ofclaim 1, wherein the UV source is a UV light emitting diode.
 4. The UVTbiopolymer photocatalytic structure of claim 1, wherein the UV source isdirect sunlight.
 5. The UVT biopolymer photocatalytic structure of claim1, wherein the UVT biopolymer layer comprises modified acrylics.
 6. TheUVT biopolymer photocatalytic structure of claim 1, wherein the UVTbiopolymer layer comprises polylactic acid.
 7. The UVT biopolymerphotocatalytic structure of claim 1, wherein the UVT biopolymer layercomprises fluoropolymers.
 8. The UVT biopolymer photocatalytic structureof claim 1, further comprising a filler in one of the UVT biopolymerlayer or the nanophotocatalytic layer.
 9. The UVT biopolymerphotocatalytic structure of claim 8, wherein the filler is fused quartz.10. The UVT biopolymer photocatalytic structure of claim 8, wherein thefiller is sapphire.
 11. The UVT biopolymer photocatalytic structure ofclaim 8, wherein the filler is nanosilica.
 12. The UVT biopolymerphotocatalytic structure of claim 1, further comprising glass in one ofthe UVT biopolymer layer or the nanophotocatalytic layer.
 13. The UVTbiopolymer photocatalytic structure of claim 1, further comprising afiller in one of the UVT biopolymer layer or the nanophotocatalyticlayer.
 14. The UVT biopolymer photocatalytic structure of claim 1,wherein activation of the nanophotocatatlytic layer reduces ambientbacteria, viruses, VOC, or odors.